This invention relates to apparatus for dispensing uniform lengths of sheet material from a roll. The invention is especially well-suited to the dispensation of a sheet boneguard material used as a protective meat-packaging sheet placed between bones and external packaging materials.
There are many measuring dispensers capable of dispensing uniform lengths of toweling and other sheet materials. In some instances, the roll of sheet material is supported by a pair of support rollers, the angular movement of one such roller being limited to permit the release of a precise and uniform length of material. Various other dispensers limit the angular rotation of so-called measuring rollers to govern the length of material dispensed. However, in these systems, the mechanisms for stopping and releasing the measuring rollers has been rather complex, often involving ratchet mechanisms, floating cams, timing mechanisms, crank-operated slides or other components with a large number of moving parts which renders them inherently susceptible to malfunction. Although these prior devices presumably perform satisfactorily for many purposes, it is believed that the present invention involves a significant simplification in measuring dispensers for sheet material.
The apparatus disclosed herein has many desirable features as the roll of sheet material is easily loaded into and unloaded from the dispenser without moving or removing any mechanical elements of the device. The device is easily threaded as the sheet material must be led around only a single roller. Rolls of sheet material having a wide diversity of widths may be accompanied on the single apparatus without adjustment, and the length of product dispensed may be varied with little difficulty simply by changing the length-determining rotary member of the mechanism. The length of sheet material dispensed is quite accurate as the measuring roller is provided with a large area for frictional contact and also serves as a roll-support roller. Further, the measuring dispenser is capable of being assembled for right or left hand operation with minimal modification.
In one respect, the invention comprises an apparatus with a support means for rotationally supporting a roll of sheet material to be dispensed, a rotary member which carries a projection and is rotationally driven an amount proportional to the length of sheet material withdrawn from the roll. A pivoted member includes an abutment surface movable into the path of the projection to stop rotation of the rotary member. Means are provided for moving the pivoted member from its projection-obstructing position to a second or non-obstructing position where the projection on the rotary member is capable of moving thereby. Also on the pivoted member is a reset surface which is positioned so that the projection moving toward the pivoted member arrives at the abutment surface before passing the reset surface. As the abutment surface is moved from the path of the projection on the rotary member, the reset surface is moved into said path. When the projection moves against the reset surface, the force so delivered to the pivoted member returns the pivoted member to its original projection-abutting position so as to stop the rotary member upon completion of a single 360.degree. revolution.
The invention also involves the previously-discussed mechanism in combination with a support means for the roll of sheet material, such support means including a pair of spaced rollers underlying the roll of sheet material and being spaced apart a distance less than the diameter of the roll of sheet material so as to support the roll of sheet material for dispensation and to enable convenient placement and removal of the rolls of sheet material from the support means.
The invention also involves the aforementioned mechanism in combination with a replacement rotary member of different diameter than the original rotary member to enable a substitution for variation of the length of sheet material dispensed. Further inventive concepts contemplated within the invention are disclosed in the following description and embodied in the claims submitted herewith.